This invention relates to a writing instrument adapted, responsive to a pressure applied to a pen core, to supply ink stored in an ink chamber inside a pen shaft to the pen core.
There has heretofore been known a writing instrument adapted, responsive to a pressure applied to a pen core, to supply ink stored in an ink chamber inside a pen shaft to the pen core. One example of such a writing instrument is shown in FIG. 13. A writing instrument 100 comprises a valve body 60 operable, responsive to a pressure applied to a pen core 5 and the release of the pressure, to be moved in the axial direction of a pen shaft 3, wherein the valve body 60 opens and closes an ink supply passage 10 leading to the pen core 5, so as to controllably supply ink from an ink chamber 2 to the pen core 5. More specifically, the valve body 60 is supported in an axially movable manner by a support member 7 disposed to surround the ink supply passage 10 leading to the pen core 5, while receiving a biasing force toward the front end of the pen shaft 3 from a pressing spring 8 which is also supported by the support member 7, whereby in response to the movement of the valve body 60 in a direction getting close to or away from a valve seat 91 (the inner wall of the ink supply passage 10), a tapered portion 60a of the valve body 60 is brought into contact with or released from the valve seat 91 to close or open the ink supply passage 10. In this writing instrument 100, the ink in the ink chamber 2 enters from the ink chamber 2 into the inner space of the support member 7 through a communication channel 11 formed in the support member 7. Then, when the tapered portion 60a of the valve body 60 is released from the valve seat 91, the resultingly opened ink supply passage 10 allows the ink in the support member 7 to be supplied to the pen core 5.
As shown in FIG. 14, in the above writing instrument 100, the communication channel 11 leading from the ink chamber 2 to the inner space of the support member 7 is configured to consistently maintain the communication therebetween independently of the operation of the valve body 60 for opening or closing the ink supply passage 10, so that the ink in the ink chamber 2 is allowed to enter and reside in the inner space of the support member 7. Thus, pigments and others contained in the ink are liable to be deposited in the inner space of the support member 7, and the deposited pigments can cause the risk of disturbing a proper movement of the valve body 60 due to their clogging between the windings of the pressing spring 8 or the like. Particularly when an ink with a high content of pigment is used, this phenomenon becomes obvious. While the ink stored in the ink chamber 2 can be stirred through a technique of containing a stirring weight in the ink chamber 2 and shaking the writing instrument 100 to move the stirring weight around the ink chamber 2, such a stirring weight cannot be received in the inner space of the support member 7 because of the design in which the valve body 60 is essentially located therein. Thus, it has been difficult to sufficiently stir the ink in the inner space of the support member 7 so as to eliminate deposits in the inner space of the support member 7.
It is an object of the present invention to provide a writing instrument which is free from the problem residing in the prior art.
It is another object of the present invention to provide a writing instrument which can reduce the deposit of ink pigments around a valve body for controlling the ink supply to a pen core to minimize occurrence of defect in the operation of the valve body.
According to an aspect of the invention, a writing instrument supplies ink from an ink chamber inside a pen shaft to the pen core through an ink supply passage in response to a pressure axially applied to the pen core. The writing instrument comprises a valve seat disposed between the ink chamber and the pen core, a valve body operable, responsive to a pressure applied to the pen core, a biasing member for biasing the valve body to keep the valve body in the close position, and a support member disposed inside the ink chamber to surround the valve seat and at least a portion of the valve body to be brought into contact with the valve seat.
In the writing instrument, the support member includes a communication channel for communicating the inner space of the support member with the ink chamber, and the valve body has a channel control portion for allowing the ink flow through the communication channel to be more restricted when the valve body is in the close position than when it is in the open position.
Other features and advantages of the present invention will be apparent from the accompanying drawings and from the detailed description.